The invention is directed to a communication arrangement with a private communication system to which private communication terminal equipment that are not directly connectable are allocated.
Private communication networks are formed by private communication systems that are partly or fully integrated with one another. The integrating of the private communication systems is partially achieved via private property and partially via public communication networks. In particular, the public analog and the integrated services digital telephone communication network--referred to in the field as the ISDN network--as well as digital data networks--for example, the packet network or a synchronous through-connection network--particularly represent public communication networks. The private communication systems can be differently designed in view of their configuration size; however, a uniform signaling is provided in the private communication network. Since the signaling in private communication networks comprises substantially more signaling versions compared to the signaling in the public communication networks (particularly caused by the additional performance feature control), consequently additional signaling information are to be communicated, and additional signaling paths or signaling channels conducted via the public communication networks are required. EP0 642 282 A1 discloses that the additional signaling path between communication systems is to be realized with the assistance of an additional means over an analog telephone communication network, over a separate channel of a data communication network, or by an overlay connection over a telephone connection.
In private communication networks, further, isolated or a few communication terminal equipment units, i.e. communication terminal equipment units that cannot be connected to a communication system via private property are connected to a private communication system. The advantageous, additional performance features of a private communication network, however, should thereby be preserved. Up to now, exclusively used transmission lines, i.e. hard-wired connections in public communication networks, have been provided for the connection of such "isolated" communication terminal equipment to a communication system. Such exclusive lines are available without limitation for a transmission of information and are intrusion-proof since every connection on an exclusively used line is unambiguously reached only by the private communication network own communication system. The exclusivity of the transmission lines, however, represents a substantial financial expense for the connection of an "isolated" communication terminal equipment unit. It is also known to bring such "isolated" communication terminal equipment to a private communication system via dialed connections of a public communication network. This, however, means a substantial limitation of the performance features useable by the communication terminal equipment and, due to signaling errors or bad controls in the public communication networks, an unambiguous allocation of private communication system to private communication terminal equipment is also no longer possible.